The authors report a case of non-hodgkin's lymphoma initially presenting with pallakiuria due to a prostatic localization of the tumour. The diagnosis was confirmed 6 months later following deterioration in the general condition with lymphomatous meningitis, after repeat examination of the prostatic slides. Less than twenty cases of prostatic lesions revealing lymphoma have been reported in the literature. There are no formal diagnostic arguments apart from the histology which is often difficult to interpret. In most cases the lymphomas are disseminated and composed of large cells or cleaved small cells with a poor prognosis and a mean survival of 14 months. Treatment primarily consists of chemotherapy, as the lymphoma is always disseminated. The role of local radiotherapy is questionable.